Refactor LauncherDelegate

ash/launcher/launcher_item_delegate_manager.cc

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ash/launcher/launcher_item_delegate_manager.h"
+
+namespace ash {
+
+LauncherItemDelegateManager::LauncherItemDelegateManager() {
+}
+
+LauncherItemDelegateManager::~LauncherItemDelegateManager() {
+}
+
+void LauncherItemDelegateManager::RegisterLauncherItemDelegate(
+    ash::LauncherItemType type, LauncherItemDelegate* item_delegate) {
+  // When a new |item_delegate| is registered with an exsiting |type|, it will
+  // get overwritten.
+  item_type_to_item_delegate_map_[type] = item_delegate;
+}
+
+LauncherItemDelegate* LauncherItemDelegateManager::GetLauncherItemDelegate(
+    ash::LauncherItemType item_type) {
+  DCHECK(item_type_to_item_delegate_map_.find(item_type) !=
+      item_type_to_item_delegate_map_.end());
+  return item_type_to_item_delegate_map_[item_type];
+}
+
+}  // namespace ash